The present disclosure relates to a tantalum capacitor.
Tantalum (Ta) is a material widely used in various industries, such as in the aerospace and defense industries as well as in the electrical, electronic, mechanical, and chemical fields due to the advantageous mechanical and physical properties thereof, such as a high melting point, excellent flexibility and corrosion-resistance, and the like.
Since astable anodized film may be formed on tantalum, tantalum has been widely used as an anode material in small capacitors. Recently, in accordance with the rapid development of information technology (IT), particularly in fields such as electronics and information-communications, the annual usage of tantalum has rapidly increased.
Generally, a capacitor refers to a capacitor temporarily storing electricity therein and is a component in which two insulated flat plate electrodes are brought into proximity with each other, while a dielectric substance is interposed therebetween, and electrical charges are charged therein by attractive force, thereby allowing electricity to be accumulated. Such capacitors store electrical charges and electrical fields in a space enclosed by two conductors, such that capacitors are used to generate capacitance.
A tantalum capacitor using tantalum has a structure employing voids generated at the time of sintering and hardening tantalum powder and is completed by forming tantalum oxide (Ta2O5) on the surface of hardened tantalum using an anodic oxidation method, forming a manganese dioxide (MnO2) layer, which is an electrolyte, on this tantalum oxide as a dielectric substance, forming a carbon layer and a metal layer on the manganese dioxide layer to form a body, forming an anode and a cathode on the body for mounting on a circuit board, and forming a molding part.
Since a tantalum capacitor according to the related art has a structure in which a board layer is formed on an electrode connection portion in order to connect a tantalum material and an electrode to each other, and a connection path such as a via hole is formed in the board layer, an internal space of a molding part is small, such that it is difficult to increase efficiency of a capacitor body or variously design the structure of an anode and a cathode.
Therefore, structures in which internal lead frames are used, or terminals are exposed externally without frames, have been disclosed.
In the case of the structure using the internal lead frames, a space occupied by the tantalum material in the molding part is decreased by the internal lead frames for an anode and a cathode, and since capacitance is in proportion to volume in the tantalum material, capacitance may be limited.
In the case of the structure in which the terminals are exposed externally without the frames, since a plurality of contact materials are present, contact resistance is increased by the plurality of contact materials, such that equivalent series resistance (ESR) and equivalent serial inductance (ESL) of the capacitor may be increased.
Further, in the case of the structure in which the terminals are exposed externally without the frames, since a cathode terminal is positioned on the side of a product, a welding distance for forming a solder should be secured between the tantalum material and the cathode lead frame, such that an internal volume ratio of the tantalum material may be decreased. Therefore, the capacitance may be decreased.
A capacitor including a tantalum element is disclosed in the following Patent Documents 1 and 2, but Patent Document 1 discloses a structure in which a tantalum wire is formed on one side of the tantalum element and connected to an anode via a reinforcing material, and Patent Document 2 discloses a structure in which a tantalum wire is led to one side of the tantalum element so as to be inclined.